Sampling and testing of biological samples and body fluids (e.g., saliva, blood, urine, fecal matter, foods, plants, fish, minerals, animals, etc.) is common for both testing and monitoring humans, fish, animals, and plants for any number of biochemical or physiological conditions and, of course, for determining the general state of health of an organism. For example, sampling and testing of human body fluids is often performed for point-of-care testing (“POCT”). POCT is defined as medical testing at or near the site of patient care. The driving notion behind POCT is to bring the test conveniently and immediately to the patient. This increases the likelihood that the patient, physician, and care team will receive the results more quickly. This allows for immediate clinical management decisions to be made. POCT examples include, but are not limited to, blood glucose testing, metabolic testing (e.g., thyroid stimulating hormone), blood gas and electrolytes analysis, rapid coagulation testing, rapid cardiac markers diagnostics, drugs of abuse screening, urine testing, pregnancy testing, fecal occult blood analysis, food pathogen screening, hemoglobin diagnostics, infectious disease testing, cholesterol screening, cancer testing (e.g. PSA), hormone testing (hCG, LH, FSH), cardiac (troponin), pulmonary, gastroenterology (e.g., H. pylori antibodies), urology, nephrology dermatology, neurology, pediatrics, surgical, and public health (Ebola, cholera, HIV, malaria), and combinations thereof.
One testing method that is often employed for POCT and more conventional testing involves the use of lateral-flow chromatographic immunoassay cassettes. Lateral-flow chromatographic immunoassay cassettes can be used to easily and quickly obtain a variety of qualitative results relating to a number of biochemical and physiological conditions and disease states of an individual. These kinds of tests require the end user to simply add a sample to the cassette and then observe the result a few minutes later. Since such rapid and easy-to-use tests are user friendly, they are very popular in both the professional and consumer markets nowadays. Such tests are also very popular in areas where access to trained health care professionals is limited or where access to proper medical facilities is limited (e.g., poor areas, developing countries, war zones, etc.).
At present, there exists no means for performing more complex blood tests (e.g., a CBC, CD4+ T lymphocyte count, bacterial cell count, detection of circulating parasites such as intra-erythrocyte malaria pathogens and filaria, and the like) at point-of-care or in a resource-limited setting. For example, there are well-known automated and manual methods for performing a CBC, but either class of methods requires complex and expensive instrumentation and highly skilled operators. Likewise, samples (e.g., blood) must be collected, prepared and sent off for testing, which is time-consuming. Consequently, there exists a need in the art for simple, robust technologies that can perform a blood test at the point-of-care or in a resource-limited setting to allow medical practitioners to diagnose a variety of conditions without being tied to a medical facility or a testing laboratory.